Power System Relay Protection Codes

The widely used United Sates standard ANSI/IEEE C37. 2 'Electrical Power System Device Function Numbers, Acronyms, and Contact Designations' deals with protective device function numbering and acronyms. Even in those parts of the world where IEC standards are predominate, the use of ANSI numbering. These numbers are based on a system that is adopted by a standard for automatic switchgear by Institute of Electrical and Electronics Engineers (IEEE), and incorporated in American Standard C37. These types of devices protect electrical systems and components from damage when an unwanted event occurs, such as an electrical. [pdf]